Q: I’m fortunate enough to have bought a house last year with a decent sized garden out the back. I didn’t touch the garden last year, but I’m keen to dig into it this year. Unfortunately, it has loads of bindweed – next door is also affected, so I guess it has been established for a number of years. My question is whether I absolutely must remove it, or if it can coexist without killing any planting I do this year? MR
A: The bane of many older, established gardens, hedge bindweed (Calystegia sepium) is a native plant that’s easily identified by its white trumpet-shaped flowers, heart-shaped green leaves and long, slender-twisting stems that twine themselves around host plants and suppress growth. Its relative, field bindweed (Convolvulus arvensis), is also a very challenging garden weed for the same reason. So I’d definitely recommend doing your very best to control this problem before planting.
I say “control” because unfortunately bindweed is one of those deciduous perennial weeds that’s pretty much impossible to fully eradicate once it gets hold. This is especially true of a town garden like yours where the plant is also growing in adjoining gardens.
Bindweed spreads and overwinters via a fast-growing, creeping network of brittle white rhizomes (typically found within the upper 30cm layer of soil) and stolons (found on the surface of the soil) and can potentially regenerate from even small root fragments to produce long climbing stems that can reach a height of two-four metres long in just one growing season. So even if you did miraculously manage to dig out every tiny part of the root system, it will almost certainly begin to recolonise via other parts of the plant living in your neighbours’ gardens.
The conventional non-organic method of control is to apply weedkiller, but this would take repeated applications and, along with being environmentally destructive, would only ever be effective in the short term.
The recommended organically-acceptable method – a labour-intensive one – is to use a garden fork to repeatedly dig out and remove as much of the plant as you can over a period of time to weaken it and to then restrict its re-emergence by regular hoeing and hand-weeding.
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Initially you’ll need to dig the area over at least several times over several months, each time doing your best to remove as much of the plant fragments as you can, paying special attention to areas around the roots of established plants, hedges, and out-of-the-way corners of the garden. All fragments of the plant should then be put in a strong bag and left to fully rot down.
Cultivating the soil with a fork and/or spade will also help to restrict its growth as bindweed thrives in undisturbed ground. Tedious as it sounds, I’ve successfully managed it this way in the past and have been impressed by how surprisingly effective it is as a weed-control strategy just so long as it’s done consistently.
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But tackling the roots, rhizomes, stolons and stems that will do their best to invade from neighbouring gardens is inevitably going to be an ongoing challenge requiring vigilance as well – ideally – as a collective approach. Could you have a friendly conversation with your neighbours to try to agree on a shared commitment to controlling it? Other ways to help control but not eradicate it include turning badly infested areas over to lawn (if regularly mowed, this will weaken the plant); using a weed-suppressant membrane; and burying solid vertical barriers (for example, lengths of corrugated iron) below ground right next to garden boundary fences or hedges to help stop it recolonising your plot.